Paragliders

19 August 2024

Folding a rectangular piece of Bienfang tracing paper and gluing the edges together can provide the necessary stiffness for a paraglider's sail. For ease of flight adjustment and to prevent the ends from collapsing and disrupting the balance, fold the tips of the sail over longer balsa sticks. Two sets of strings, tied to a pendant weight, will be looped over the ends of these sticks.

5 August 2024

An indoor model paraglider using Bienfang tracing paper as the sail but uses a truss structure made of balsa sticks to support the sail and the weight. Using threads/fishing lines or similarly flexible material may be more to realistic, but it is less forgiving for a simple-to-fly indoor model paraglider.

The truss structure consists of 2 identical triangles made of 1/16" square balsa sticks, joined at the apex where the weight is attached and spread apart by a cross brace (also of balsa sticks) in the middle of the adjacent sides and hypotenuse sides. A simple rectangular piece of Bienfang tracing paper, with the length slightly longer than the separated adjacent sides is glued to the adjacent sides and this completes the very small indoor model paraglider.

2 August 2024

paragliders: lightweight, free-flying, foot-launched glider aircraft with no rigid primary structure.

An indoor model paraglider using Bienfang tracing paper

The intention is to make a small glider without rigid primary structure and successfully glide it in an indoor environment. 

A real paraglider has no rigid primary structure, and yet it manages not to collapse upon itself because the sailcloth is stitched to form a ram-air structure. I don't want to even try and replicate it on a miniature model gliding indoors.

Let's replace the ram-air structure by changing the design and material. Firstly, make a single-skin sail from Bienfang tracing paper. To this single flat (and unstable) airfoil, we want to stiffen it chord-wise and we can do that by folding the tracing paper upon itself. Do it a few times and we will have as many integral paper ribs (without camber) as we wish. To these ribs, rig the underslung weight for balance and we are done.

An alternative method is to fold the single sail into an accordian stack and punch holes into it to allow rigging the underslung weight for balance.

Rigging the underslung weight

The weight is a piece of metal nut, washer or even a nylon foam wheel. The hole will allow the rigging lines to pass through, simplifying the tying of the weight.

For the moment, the rigging lines are designed to be identical and the most important aspect of each set of rigging line (fore and aft) is to hold the sail (relative to the weight) at the same pitch as the other sets. Making the rigging lines identical will be very time-consuming. A jig is therefore necessary and I am thinking of using paper stapler's staples to fabricate simple hooks.